I’ve been really busy incorporating a new compiler into Clasp to eventually allow it to generate performant code. My goal is code that runs as fast as the best Common Lisp compilers out there (I’m looking at you Steel Bank Common Lisp! :-)).
I’m also incorporating a pointer tagging scheme within Clasp so that FIXNUM, CHARACTER, SHORT-FLOAT (32bit IEEE float) and SINGLE-FLOAT (a hacked 59bit pseudo double-precision representation) are all immediate values. CONS cells will have their own tag as well to make iteration over Common Lisp LISTs as fast as possible.